Alternator-rectifier control circuit



May 29, 1962 R. A. CARLSON I ALTERNATOR-RECTIFIER CONTROL CIRCUIT FiledDec. 11, 1957 'i ll INVENTOR.

United States Patent Ofifice 3,037,124 Patented May 29, 1962 3,037,124ALTERNATOR-RECTIFIER CONTROL CIRCUET Richard A. Carlson, Clarkston,Mic-11., assignor to General Motors Corporation, Detroit, Mich, acorporation of Delaware Filed Dec. 11, 1957, Ser. No. 702,000 6 Claims.(Cl. 290-36) This invention relates to motor vehicle electricalcircuitry, and more particularly to a control circuit wherein the outputof a generator is used as a signal voltage to control various switchingoperations in the circuit. This control system is designed to operatewith any alternatingcurrent generator-rectifier combination which has anelectrical or electromechanical means of controlling generator fieldcurrent.

An object of this invention is to provide an electrical circuit whereina generator feeds a plurality of loads including a storage battery andwherein circuitry is provided for preventing energization of certain ofthe loads by the storage battery when the generator is not producing anoutput voltage. With this arrangement, the battery cannot be quicklydrained of its stored power by the connection of the battery to ahigh-current load, and thus, the possibility of draining the batteryinadvertently by the operator of a bus or passenger car is eliminated.

Another object of this invention is to provide a circuit for anelectrical starting motor that forms a part of a vehicle electricalsystem that includes a generator, and wherein the starting motor isprevented from being energized when the generator is producing an outputvoltage.

Still another object of this invention is to provide a chargingindicator circuit for a battery-charging circuit that includes a storagebattery which is fed by an alternator through one or more rectifiers,the indicator circuit including an indicator which indicates when thegenerator is producing an output voltage, and which indicates adischarge condition when the battery is supplying current to the load.

A further object of this invention is to provide a circuit includingswitch mechanism for connecting the output of a generator with a voltageregulator in such a manner that the voltage drops through the leadsconnecting the generator and the regulator are maintained at a minimum.This feature of the invention is highly important in buses where thecontrol switches are located at one end of the bus and the generator atan opposite end thereof, and where relatively long lead wires are usedfor controlling certain switching functions.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawing:

The single FIGURE drawing illustrates a control circuit for a bus orother motor vehicle made in accordance with this invention.

Referring now to the single FIGURE drawing, an alternating-currentgenerator generally designated by reference numeral 10 is shown. Thegenerator is of the brushless type shown in copending application S.N.589,759, filed June 6, 1956, and includes a fixed field winding 12, afixed three-phase, Y-connected output winding 14, and a metal rotor 16that rotates between the field and output windings. The output winding14 is connected with rectifiers 18 and 20 that are circuited in athree-phase full-wave bridge rectifier network having DC. outputterminals 22 and 24. The output terminal 22 is grounded as shown,whereas the output terminal 24 is connected with a lead 26. The bridgerectifier has a third output terminal 28 that is connected betweenrectifiers 18 and 20. With this arrangement, full-wave output current issupplied between terminal 24 and ground and half-wave current issupplied between terminal 28 and ground. The rotor 16 of alternator 10is drivably connected with the drive shaft of an engine 32 that may be adiesel engine that supplies the motive power for a bus or the like.

The lead 26 that is connected with rectifier terminal 24 is connected toone side of a manually-operable diesel run switch 34 by means of a lead35. A storage battery 36 is connected between the line 35 and ground,and the line 35 thus carries charging current to the battery 36. Theopposite side of switch 34 is connected to one side of amanually'operable starter switch 37 by a lead 38, and to an inputterminal 39 of a voltage regulator 40 by means of lead 41.

The voltage regulator 40 is of the type described in copendingapplication S.N. 621,833, filed November 13, 1956. The regulator has aground terminal 42 that is connected to ground, and a field terminal 43that is connected to one side of alternator field winding 12 by a lead44. The opposite side of the field winding is grounded as shown. Theregulator, as described in application S.N. 621,833, has a transistorconnected between input terminal 39 and field terminal 43 to control thefield current passing between input terminal 39 and the grounded side offield winding 12. The conduction of the transistor is controlled as afunction of the voltage appearing across the rectifier output terminals22 and 24 which voltage appears across terminals 39 and 42 of thevoltage regulator 40. The terminals 39 and 42 thus are the sensingterminals of the voltage regulator, and the voltage across theseterminals controls the field current in field winding 12. It will bereadily apparent that any other type of voltage regulator may be used aslong as the field current in field winding 12 is controlled as afunction of the voltage appearing across rectifier terminals 22 and 24.

The side of switch 37 opposite from lead 38 is connected to theactuating coil 46 of a relay generally designated by reference numeral47, by means of a lead 48. The relay 47 has an armature 49 that carriescontacts 50 and 51 which co-operate respectively with fixed contacts 52and 53. The armature 49 is mechanically and electrically connected witha relay frame 54 that is, in turn, connected with one side of a starteractuating coil 55 by a lead 550, the opposite side of the coil 55 beinggrounded.

The starter actuating coil 55 forms a component part of a conventionalelectric starter generally designated by reference numeral 56. Thestarter includes the coil 55, an armature 57 that is actuated by thecoil, a starter motor 58, and a drive pinion gear 59. The motor 58 hasarmature and field windings designated in their entirety by referencenumeral 60 and has a shaft 61 connected with drive pinion 59. A linkmember 62 is connected between armature 57 and drive pinion 59, the linkmoving the drive pinion into engagement with a ring gear 63 that isfixed to drive shaft 30 of engine 32 when the coil 55 is energized. Thearmature 57 carries a contact plate 64 that short circuits contacts 65when the coil 55 is energized. One of the contacts 65 is connected withjunction 78 and to one side of battery 36 by a lead 66a, whereas theother contact is connected to one side of the field and armature winding60 of motor 58, the other side of windings 60 being grounded. With thisarrangement the starter motor 56 will crank the engine 32 whenever theactuating coil 55 is energized by shifting the drive pinion 59 intoengagement withring gear 63 and by s,os7,124

shorting contacts 65 to provide a circuit for motor Windings 60.

The side of actuating coil 46, opposite from the side connected to lead48, is connected with the frame 66 of a relay generally designated byreference numeral 67 by a lead 67a. The relay has an armature 68 thatcarries contacts 69, 70 and 71-, the armature being mechanically andelectrically connected to frame 66. The contacts 69, 70 and 71,co-operate respectively with fixed contacts 72, 73' and 74. The fixedcontact 74 is connected with a lead 75 that is, in turn, connected tothe input terminal 39 of voltage regulator 48. The fixed contact 72 isconnected directly to ground, as shrown, while the fixed contact 73 isconnected to a lead 76 by a lead 77. The lead 76 is connected betweenfixed contact 53 of relay 47 and the junction point 78 which connectsleads 26, 35 and 76. The actuating coil 79 of relay 67 has one of itssides connected directly to rectifier terminal 28 by a lead 80. Theopposite side of relay coil 79 is connected with the fixed contact 52 ofrelay 47 by a lead 81.

The motor vehicle circuit described has an electrically energizable load82 of high current capacity that is grounded at one side thereof. In amotor-driven bus, this lead may take the form of an electric blowermotor for a blower or may be any other high current device that will puta heavy drain on the battery 36 if the device is energized by thebattery for a relatively short period of time. The opposite side of load82 is connected with a lead 83 through a manually operable switch 84.The lead 83 is connected directly to lead 670. An electrical load 85 hasone side thereof connected to lead 83 and has its other side grounded.The load 85 represents cer tain electrically-operated safety devicesthat are used on motor-driven buses.

An electric lamp having a filament 86 is connected between leads 75 and83. This lamp, as will be more readily apparent hereinafter, will lightup when the battery 36 is discharging and will be extinguished when thegen erator is developing an. output voltage. The circuit may be providedwith another charging indicating device that takes the form of aconventional electrically-energizable meter generally designated byreference numeral 87; The meter has actuating coils 87a and 87b whichare connected respectively to leads 75 and 83. The actuating coils areconnected together and to a junction point 88 which is grounded. Themeter has a pointer 89 which is moved in accordance with theenergization of coils 87a and 87b. When both coils are energized withequal voltages, the pointer remains in a vertical position. If the coil87a is energized with a greater voltage than coil 87b, the pointer 87moves leftwardly, whereas when coil 87b is energized with the greatervoltage, the pointer moves rightwardly. It will be readily apparent tothose skilled in the art that one of the chargingindicators might beeliminated if both are not desired.

The operation of the above-described circuit will now be described. Whenit is desired to start the engine 30, the diesel run switch 34 isclosed. This connects the battery 36 with terminal 39 of voltageregulator 40, thereby supplying current to the field 12 of generator 10.The closure of switch 34 also connects one side of battery 36 with oneside of signal lamp 86 and to coil 87a of meter 87 via line 35, switch34, line 41, and line 75. The lamp 86 will light up since at this pointof time the lead 83 is connected directly to ground via lead 67a, frame66 of relay 67, armature 68 of relay 67, and contacts 69 and 72 of relay67. The pointer 89 of meter 87 will deflect leftwardly at this time dueto the fact that both sides of coil 87b are grounded while coil 87a isenergized with battery voltage. The leftward deflection of pointer 87aand the lighting up of lamp 86 thus both indicate a dis chargingcondition of the battery.

After switch 34 has been closed, the starter switch 37 is closed toenergize coil 55 of starter 56 and thus begin the cranking of engine 32.The closure of switch 37 completes a circuit for relay coil 46 which maybe traced from battery 36, through line 35, switch 34, line 38, switch37, line 48, coil 46, line 67a, frame 66 of relay 67, armature 68 ofrelay 67, and through contacts 69 and 72 to ground. When relay coil 46is thus energized, the armature 49 of relay 47 is attracted downwardlyto open contacts 50 and 52 and close contacts 51 and 53-. The closure ofcontacts 51 and 53 closes a circuit for starter solenoid 55 that may betraced from battery 36, through line 35, line 76, contacts 51 and 53 ofrelay 47, armature 49 of relay 47, fra'n1e54 of relay 47, line 55a, andthen through coil 55 to ground. It is to be noted here that the armature49 is normally in the position shown in the drawing and remains in thisposition until coil 46 is energized.

When engine 32 starts, the switch 37 is released and moves to an openposition, thus breaking the circuit for relay coil 46 and permitting thearmature 49 to move upwardly to open contacts 51 and 53 and closecontacts 58 and 52. With the engine running, a voltage is generated inoutput winding 14 which is rectified to direct current. When thegenerator is producing an output voltage, the coil 79 of relay 67 isenergized with halfwave current from rectifier terminal 28. This circuitmay be traced from rectifier terminal 28, through line 80, coil 79, line81, contacts 52 and 50 of relay 47, armature 49 ofrelay 47, frame 54 ofrelay 47, line 55a, and through coil 55 to ground. The starter coil 55is not energized suiiiciently to move pinion gear 59 into mesh with ringgear 63, nor is it energized suificiently to short contacts 65, becauseonly half-wave current is passing through coil 79 and starter coil 55.This half-wave current flowing through coil 79 is sufilcient, however,to cause attraction of armature 68 downwardly to open contacts 69 and'72, and close contacts'71 and 73, and contacts 70 and 74. When thearmature 68 is in its lower position, the circuit for relay coil 46 isopen due to the opening of contacts 69 and 72, and thus armature 49 ofrelay 47 cannot be attracted to complete a circuit for starter coil 55through contacts 51 and 53. It thus is apparent that starter coil 55cannot be energized from battery 36 as long as generator it) isdeveloping an output voltage to energize relay coil 79 from rectifierterminal 28.

The closure of contacts 71 and 73, and contacts 70 and 74, and theopening of contacts 69 and 72, which only occurs when the generator 10is developing an output voltage, provides for important switchingfunctions in the circuit described, other than for preventing theoperation of starter 56. When contacts 70 and 74, and contacts 71 and 73are closed, the line 83 is connected with rectifier terminal 24 via line26, line 76, line 77, contacts 71 and 73, armature 68, frame 66, andthrough line 67a to line 83. With line 83 connected to terminal 24, theloads 82 and may be energized, because they are now connected betweenrectifier terminal 24 and ground. On the other hand, with generator 10not developing an output voltage, the relay coil 79 stays in ade-energized condition, and the armature 68 moves to its upper poistoinwherein contacts 71 and 73 and contacts 70 and 74 are opened andcontacts 69 and 72 closed. In this position of armature 68 the lead 83is grounded, and the loads 82 and 85 cannot be energized because theiropposite sides are connected to ground. It will be apparent from theforegoing that loads 82 and 85 can only be energized when the generator10 is producing an output voltage. This arrangement prevents connectionof the loads 82 and 85 with the battery 36 when the generator 10 is notproducing an output voltage, such as when the engine 32 is shut down,and thus prevents inadvertently quickly draining the battery 36 of itsstored power.

The closure of contacts 71 and 73, and contacts 70 and 74 in response tothe development of a voltage by generator 10 also connects inputterminal 39 of voltage regulator 40 with rectifier output terminal 24.This circuit may be traced from rectifier terminal 24, line 26, line 76,line 77, contacts 71 and 73, contacts 70 and 74,

and thence through line 75 to regulator terminal 39. To understand thedesirability of this switching function, it is necessary to be cognizantof the physical layout of the components of this circuit on amotor-driven bus. The engine 32, relays 4'7 and 67, starter 56,generator 10, and rectifiers l8 and 20 are all located closely adjacentto one another at the rear of the body of the bus, whereas the switches34 and 37 are located in the drivers compartment at the front of thebus. The leads connecting the switches 34 and 37 and the othercomponents of the circuit illustrated will thus be relatively long ascompared to the length of the leads that connect the other componentparts of the circuit, such as lead '75 which connects contact '74 andterminal 39 of regulator 40. It thus can be seen that if the voltagewere supplied to terminal 39 from rectifier terminal 24 via leads 3% andll, a larger voltage drop would exist across these leads than wouldexist by feeding terminal 39 by leads 76 and 75. This voltage drop in alow voltage system, such as used on buses or motor vehicles, may greatlyreduce the accuracy of control of the voltage regulator 40. With theswitching circuit described, however, the terminal 39 of regulator 40 isconnected to rectifier terminal 24 by relatively short leads thusreducing the voltage drops in the connecting leads to a minimum andinsuring the supplying of an accurate control voltage to regulator 40.

The closure of contacts 71. and 73, and contacts 70 and 74 in responseto the development of an output voltage by generator produces stillanother control function in the circuit illustrated. When these contactsare closed as aforesaid, the opposite ends of lamp 86 are at the sameelectrical potential so that the lamp 86 is extinguished indicating thatthe generator is putting out an output voltage. The coils 87a and 87b ofmeter 87 in this mode of operation have equal voltages impressed acrossthem so that pointer 89 remains in a vertical position, also indicatingthat the generator 10 is developing an output voltage.

From the foregoing it will be observed that relay 67, which responds tothe presence or absence of generator output voltage, controls thecircuit shown to prevent operation of starter 56 while generator 10 isproducing an output voltage. The relay 67 also operates to preventenergization of loads 82 and 85 when the generator is not producing anoutput voltage and controls the operation of signals 86 and 87 and theswitching of signal voltage to terminal 39 of regulator 40.

While the embodiments of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. In a motor vehicle electrical system, a generator, a storage battery,means connecting the output terminals of said generator with theterminals of said storage battery, and electrically-enengizable load,means for at times energizing said load from said generator, and meansresponsive solely to the value of geneator output voltage for preventingenergization of said load by said storage battery when said generator isnot developing an output voltage and regardless of storage batteryvoltage.

2. In a motor vehicle electrical system, a generator having outputterminals connected with a load circuit, a storage battery havingterminals connected with said load circuit, an electrically-energizableload, and means responsive solely to the value of generator outputvoltage for connecting said load with said load circuit when saidgenerator is developing an output voltage and for disconnecting saidload from said load circuit when said generator is not developing anoutput voltage regardless of storage battery voltage.

3. In a motor vehicle electrical system, an alternatingcurrent generatorhaving output terminals, a rectifier connected with the output terminalsof said generator and connected with a direct-current load circuit, astorage battery connected with said load circuit to be charged thereby,an elcctrically-energizable load, a relay having an actuating coil and apair of normally-open contacts connected between said load circuit andsaid load for completing a circuit between said load circuit and saidload when said actuating coil is energized, and means for energizingsaid actuating coil to close said contacts solely in response to thedevelopment of an output voltage by said generator and regardless ofstorage battery voltage.

4. in a motor vehicle electrical system, an alternatingcurrent generatorhaving a three-phase output winding, a three-phase full-wave bridgerectifier connected with said output winding and having a pair of outputterminals connected with a DC. load circuit, a storage battery connectedwith said load circuit, an electrical load, a relay having an actuatingcoil and a pair of normally open contacts connected between said loadcircuit and said load for completing a circuit between said load circuitand said load when said actuating coil is energized, means con nectingone side of said actuating coil to one of said rectifier outputterminals, and means connecting an opposite side of said actuating coilto the junction point of two rectifiers of said bridge rectifier circuitwhereby said actuating coil is energized with half-wave current andoperates to close said contacts when said enerator is developing anoutput voltage.

5. In a motor vehicle electrical system, the combination comprising, agenerator, a battery, a charging circuit connecting said generator andbattery, an electrically energizahle load, and means responsive solelyto generator output for controlling the connection or" said storagebattery with said load, said means preventing energization of said leadby said battery when said generator is not developing an output voltageregardless of battery voltage.

6. In a motor vehicle electrical system, the combination comprising, analternator, a battery, rectifier means connected between said alternatorand said battery for supplying charging current to said battery, anelectrically energizahle load, and means connected with at least aportion of said rectifier means and responsive solely to the outputvoltage of said rectifier means for controlling the connection of saidstorage battery with said load, said means preventing energization ofsaid load by said battery when said alternator is not developing anoutput voltage regardless of battery voltage.

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